This invention relates to light fittings and refers particularly, though not exclusively, to light fittings for use in swimming pools.
For many years lights have been provided in in-the-ground swimming pools by being built into the wall. These lights have all used incandescent lamps and glass covers to protect the lamps. The use of glass covers results in no control over light output and hence the light fitting illuminates the pool and all surrounds. The resultant glare can dazzle people using the pool and thus cause accidents. Furthermore, to replace the lamp normally required the fitting to be completely removed and completely dissembled. This is, naturally, of great annoyance to users.
Examples of the prior art systems are shown in U.S. Pat. Nos. 3,337,725 of Nash and 3,339,066 of Hart, the Nash specification discloses a system whereby the light source is located remote from the swimming pool and a tube with reflectors is used to transmit the light to the swimming pool wall. This solved two great problems--the sealing of the lens under water, and the accessability of the light source. Unfortunately, the operation of the light was extremely inefficient due to the reduction in light at the reflective surfaces, and the cost of installation was extremely high. Furthermore, the actual light source assembly was complex and bulky with the resultant difficulty in handling and maintenance by an untrained person.
The Hart specification discloses an underwater light of rather conventional construction except that a sealed beam lamp is used. In doing this, the actual housing need not be waterproof--only the electrical connections need be waterproofed. This was done by the use of an epoxy resin. The only difference between the Hart fitting and the standard prior fitting was the use of a sealed beam lamp rather than an incandescent lamp and a multi-part assembly to house that lamp.
Neither of these provide a relatively compact and efficient unit which is easily maintained by an untrained person and which eliminates complex structures required for sealing the electrical connections.
Furthermore, neither of the above prior art specifications disclose a light fitting for underwater use wherein there is provided a lens whereby the light emanating from the lamp is diffused so as to prevent unnecessary glare from the light fitting. Lenses of this general nature are known. For example, U.S. Pat. No. 2,033,381 of Koubek et al shows an automotive light with a lens having a number of flutes or ribs on its internal surface which are designed to diffuse the light. U.S. Pat. No. 2,916,607 of Bargman also shows an automotive light with a lens having a number of concentric ribs on its internal surface which are also designed to diffuse the light. The lenses of the Koubek and Bargman specifications are both of the general nature of `ring optics` as are shown in U.S. Pat. No. 1,916,514 also of Koubek, where prisms on one surface of the lens and flutes on the other are arranged to totally diffuse all light.